Project Summary/Abstract The overall goal of this project is to understand the cell biophysical mechanisms regulating transmembrane signal transduction, i.e. signal transfer from ligand to receptor to downstream effector. Using vascular endothelial growth factor receptor 2 (VEGFR2) as a model system, it is focused on the following major questions: (1) What mechanisms regulate the cell surface spatiotemporal organization and signaling of VEGFR2? The goal here is to determine the membrane and cytosolic factors that regulate VEGFR2 spatiotemporal organization on the cell surface (i.e. its dynamics, oligomerization state and spatial distribution), and to test the hypothesis that these factors provide a mechanism for the cell to modulate VEGFR2's response to VEGF. (2) How do inter-receptor interactions regulate VEGFR2 signaling in response to its ligand VEGF? The goal here is to quantitatively characterize VEGFR2 interactions with other receptors, starting with the antagonistic anti-angiogenic receptor CD36, and to test the hypothesis that these interactions contribute to the integration of pro- and anti-angiogenic signals. (3) What are the spatiotemporal characteristics of signal transfer from VEGFR2 to downstream effectors? The goal here is to determine the nanoscale spatial relationship and kinetics of signal transfer from VEGFR2 to its downstream effectors, starting with phosphoinositide-3-kinase (PI3K). This will allow us to quantitatively link the spatiotemporal organization of VEGFR2 to its functional consequences. The proposed diversity supplement will support a new graduate student, Jesus Vega-Lugo, in the laboratory of the PI (Dr. Khuloud Jaqaman). Mr. Vega-Lugo brings critical mathematical and computational skills that will greatly advance the analytical tools needed to conduct these studies. Specifically, he will develop colocalization analysis tools to study various VEGFR2 interactions in the context of questions 1 and 2, and a signal processing and machine learning based framework to link VEGFR2 behavior in the membrane to PI3K activation in the context of question 3. To facilitate Mr. Vega-Lugo's intellectual growth and scientific education, his training plan includes (i) immersion in fundamental coursework and in the literature, (ii) training in cutting- edge computer vision, machine learning and signal processing techniques, (iii) strong exposure to the experimental approaches that yield the data he would be analyzing, and (iv) mentored experience in writing manuscripts and grants and in oral presentations. Dr. Gaudenz Danuser, a full Professor with a long training record, will act as a co-mentor. The Jaqaman and Danuser labs will offer Mr. Vega-Lugo extensive expertise in quantitative light microscopy, a large software repository to jump-start his work, and a highly interdisciplinary environment to enrich his research training. In addition, UT Southwestern has a world-class high performance computing cluster that will facilitate his research.